Apparatus for remotely determining the angular orientation, speed, and/or direction of rotation of objects

ABSTRACT

A rotating electric field is generated in the vicinity of a rotating member, the electric field having an axis of rotation coinciding with the axis of rotation of the member. An electric-field sensing or reading device is positioned at the rotational axis of the electric field and associated therewith for detecting variations therein as the electric field passes the rotating member, and creates an electrical output whose relative phase is dependent upon the angular orientation of the rotating member.

SUMMARY OF THE INVENTION

This invention relates to an improved remote means for determining theangular orientation, speed, and/or direction of rotation of objects suchas shafts, dial or meter hands, and the like. More particularly, theinvention is concerned with electrically obtaining a signal that isindicative of the angular orientation, speed and direction of rotationof the object to be monitored without altering the interior structure orwiring of a meter or the like. In this regard, this invention embodies asubstantial improvement of my prior magnetically induced reading systemdescribed in my prior U.S. Pat. No. 3,500,365 issued Mar. 10, 1970.

In electric utility systems, sufficient power-generating equipment mustbe provided at all times to supply power during relatively short periodsof maximum consumption, however much of this equipment otherwise remainsidle for a major portion of each day. In order to discourage high powerconsumption during maximum-demand periods by graduated billing rates, oreven to disconnect non-essential portions of a customer's load when thecustomer exceeds a previously agreed consumption rate compatible withthe optimum generating capacity of the utility company, rapiddetermination of an individual customer's consumption rate, commonlytermed "demand" over a prescribed time interval, is necessary.

Heretofore, such demand metering has generally been possible onlythrough the use of specially equipped meters, commonly limited to afixed time interval and not capable of transmitting information upondemand to a load-monitoring station in time for the station to takecorrective action. There has been considerable effort expended inproviding means and apparatus for reading meters at a distance, forexample through telephone lines and the like. Most of such previousmeter readings have required that some internal mechanical or electricalalteration be made to the meter itself and considerable time and expenseis involved in putting the altered meter into use. Further, the use ofsliding electrical contacts in previous meter reading devices haveprevented the use of such devices in explosive atmospheres; and incertain instances, changes in the output signal have been noted due tothe aging of the components which can change mechanical and/orelectrical characteristics.

Other meter reading devices have used photoelectric cells, so that nomechanical connection is needed between the meter and the meter reader.However, these reading devices have not been satisfactory because areliable source of light must be provided and the face of thephotoelectric cell must be kept sufficiently clean so that the lightimpinging on the photoelectric cell will not be diminished sufficientlyto give a false reading.

With the device described herein, conventional meters can be read by theload-monitoring station with extreme speed permitting the reading ofmany meters during a short time period, as well as taking several samplereadings from each meter to increase the statistical validity of thereadings. Thus the utility company can determine not only the totalenergy consumed by any individual customer during a normal billingperiod, but can monitor his demand rate during any desired timeinterval, using any existing meter whether demand-metering equipped ornot.

The apparatus of the present invention includes an electrical transducerunit that will indicate the hand position of a meter dial at anyparticular time without requiring mechanical connection to the meter andwithout the provisions of unreliable devices such as photoelectriccells. The only connection with the meter is through an electric field.In many cases where the meter is encased in glass, the electric fieldcan pass through the glass casing without tampering with the casing ormeter in order to install the transducer of the present invention. Inscanning the dial of a meter as hereinafter described, a rotatingelectric field can be induced without using mechanical parts that mustmove relative to one another, thereby reducing areas of possible troublewith the meter reading device. There are no spark producing switchesinvolved with the device according to the present invention, andtherefore the device can be used in explosive atmospheres.

Whereas the device described in my previous U.S. Pat. No. 3,500,365 usesa plurality of field-producing coils to generate a rotating magneticfield, and utilizes a reading coil in the center of the field producingcoils, the apparatus according to the present invention substitutes anelectric field for the magnetic field. In this regard, the fieldproducing coils are replaced by electrodes with diametrically oppositepairs of electrodes being connected to successive phases of a polyphasevoltage source in such a manner as to produce a rotating electric fieldaround the array of peripheral electrodes. In a similar manner, thereading coil is replaced by an electrode at the same central location.Any other type of electric field sensing device such as a suitabletransistor could be used. The reading electrode is connected to avoltage detector in such a way that the timing or phase of the electricfield in the vicinity of the reading electrode can be monitored.

Such a device provides several advantages over the magnetic versiondescribed in my prior U.S. Pat. No. 3,500,365. First of all, theelectrical field device is simpler and cheaper to construct since therelatively expensive coils are avoided. A smaller physical size is alsopossible by eliminating the coils, and in utility-meter readingapplications, the smaller physical size provides less obstruction tovisual checks of the dial reading. Less electrical power is requiredsince the electric field can be generated with less current than can themagnetic field. Along the same line, since less field is required withthe electric field to monitor the position of the object than with themagnetic field, the chance of influencing the meter or device to be readby a strong field is thereby minimized. The rotatable member of thepresent invention does not have to be magnetically conducting, as wasthe case with the prior device. The apparatus according to the presentinvention will work with any metal, ceramic, plastic, or other rotatingmember, such as a meter hand, whose dielectric constant differssignificantly from that of the surrounding medium, whether the medium beair, another gas, or a liquid.

These and other features and advantages of the present invention willbecome apparent from the following specification when taken inconjunction with the accompanying drawings, in which:

FIG. 1 is a schematic diagram showing a transducer according to thepresent invention in conjunction with the control circuit and arecording circuit therefor;

FIG. 2 is a schematic wiring diagram showing the connection of thetransducer with the reading circuit; and

FIG. 3 is a front view of a transducer similar to that shownschematically in FIGS. 1 and 2, except arranged to read a meter havingfive dials.

In general terms, the present invention includes means for providing arotating electric field with a reading means at the center of rotationof the electric field. Normally there would be no signal induced in thereading means, because the vector sum of all voltages read by thereading means from all points is zero voltage. However, when placed infront of a meter dial or other rotating member so that the voltagedetector or reading means is aligned with the meter shaft, a differentresult occurs. The meter hand, whose dielectric constant differs fromthat of the surrounding medium, provides a pathway between the meterhand tip position and the reading means. When the electric field passesthe meter hand or rotating member, the material of the meter handprovides a pathway (capacitive coupling) to the reading means, whichthen exhibits a sinusoidal voltage whose phase (relative to the inputphase) is directly proportional to the angular position of the meterhand. The signal can then be monitored by any of several well knownmeans so as to indicate the angular orientation of the rotating memberor meter hand, or if desired, to indicate the speed and/or direction ofrotation of the rotating member about its axis of rotation.

Referring now to FIG. 1 of the drawings, a transducer generallydesignated at 10 is positioned adjacent the face of a meter 11 having ahand 12. A reading means 14 in the form of an electrode, or otherelectric field sensing device, such as a transistor, is positioned atthe center of the transducer 10, the reading means being connected tothe wire 15 in which there is a phase comparison circuit 13 ofconventional and well-known design.

The transducer 10 is also positioned so that the axis of rotation of theelectric field coincides with the axis of rotation of the meter hand 12.

It will be understood that the wire 16 is from a source of electricalvoltage (generally single-phase), such as an electric power line or thelike. A signal monitoring device 17 of conventional design is arrangedso as to ignore routine voltage changes occurring on wire 16 but todetect special voltage patterns (which may be superimposed thereon bythe remote station and which constitute a request for a meter reading)and respond thereto by closing a switching device such as is representedby relay L1. With this arrangement the relay L1 or other switchingdevice can be remotely energized to activate the transducer 10.

The wire 16 leads to a phase splitter 18. The phase splitter 18 convertsthe single phase voltage into a plurality of phases, for example, threephases to provide the rotating electric field.

It will thus be seen that, when it is desired to read the meter 11, aninterrogation signal is placed on the wire 16 which causes the signalmonitor to energize the relay contact L1-1. When the contact L1-1 isclosed, the single phase voltage through wire 16 which will be split bythe phase splitter into a polyphase voltage, for example, as illustrateda three-phase voltage. As an inherent feature of properly connectedpolyphase voltage, an electric field will be generated that will rotatearound the face of the transducer 10. When the rotating field crosses,or becomes parallel to, the dial hand 12, a voltage change will beinduced in the reading means 14 from what would ordinarily be expected,to give an indication that the dial hand has been scanned. It is notnecessary that the hand 12 be magnetized, or even electricallyconductive, as long as the dielectric constant of the material fromwhich the hand 12 is formed differs significantly from that of thesurrounding medium. Generally, any material will work, such as metal,ceramic, or plastic.

Referring now to FIG. 2 of the drawings for a more detailed discussionof the circuit, it will be seen that the wire 16 is connected throughrelay contact L1-1 to the phase splitter 18. The details of the phasesplitter 18 are not shown herein, this being a conventional apparatus,well known by those skilled in the art, it being understood, however,that the phase splitter 18 can provide polyphase voltage, that is,voltage of two-phase, three-phase, or any other number of phases.Three-phase voltage is, perhaps, preferable because three-phase voltagewill frequently be available from the conventional power line so thatthe phase splitter 18 will not be required. If three-phase voltage isavailable from the power line, there will be three contacts such ascontact L1-1, one of the contacts being in each of the three phasewires, and the phase-splitter 18 will be replaced by threephase-inverters so that the input to the transducer 10 will consist ofthe three original phases and their inversions.

The six lines coming from the phase-splitter 18 are designated A, B, C,-A, -B, and -C, which will also designate the positive and negativepolarities of the three phases: phase A, phase B, phase C. It will beobserved that wire A is connected to electrode 25, and wire -A toelectrode 22, these two electrodes being diametrically opposed ontransducer 10. Similarly, wire B is connected to electrode 21 and wire-B to the diametrically opposed electrode 24, and likewise wire C isconnected to electrode 20 and wire -C to the diametrically opposedelectrode 23. The diametrically opposed electrode pairs 20, 23; 21, 24;and 22, 25, are each wired with one electrode, e.g. 20, connected to thepositive side of one phase (e.g. phase C), while the other electrode,e.g. 23, is connected to the negative side of the same phase. Thereforea voltage both electrodes will cause opposite polarity on each of thetwo electrodes of the electrode pair, so that an electric field will beprovided between each electrode pair 20, 23; 21, 24; and 22, 25.

With this arrangement, it will be understood by those skilled in the artthat, when phase C reaches its peak voltage, there will be an electricfield between the electrodes 20 and 23, one of the electrodes beingpositively charged and the other being negatively charged. A hundred andtwenty (120°) electrical phase degrees later, when phase B reaches itspeak voltage, there will be a strong electric field between theelectrodes 21 and 24, one of the electrodes being positively charged andthe other being negatively charged; and, the same situation will be truefor the electrodes 22, 25 when phase A reaches its peak voltage. Thus arotating electric field is provided.

At the geometric center of the peripheral electrodes 20-25 and alignedwith the axis of rotation of the hand 12 is positioned the reading means14 in the form of an electrode or other electric field-sensitive device,such as a suitable transistor. Electrically speaking, then, the meterhand 12 "samples" the electric field at the position of its tip,provides a capacitive coupling between this position and the centralelectrode, which then experiences a voltage whose phase (relative to thephase of the voltage applied to any electrode) is directly proportionalto the angular position of the meter hand. In some applications of theinvention, other than reading utility meters, it may be desirable tomeasure the speed and/or the direction of movement of the rotatingmember. In such cases the sine-wave output of the central electrode willbe distorted, and the speed and direction of the rotating object can bededuced from the amount and shape of the distortion.

Transducer 10 is more clearly shown in FIG. 3, which is schematicallyillustrative of a device for reading a meter having five dials. Abacking plate 29 in the preferred form of a printed circuit plateincludes five sets 40, 42, 44, 46, 48 of circularly arranged electrodes20-25 on the face thereof, each set corresponding to one of the meterdials. The small numbers 0-9 on the face of each set of electrodes isrepresentative only of the corresponding meter dial face (not shown)adjacent which the electrodes are positioned. A printed conductor lineor lead 30 extends from each electrode 20-25 to one of a plurality ofpunch through connectors 32 which, in turn, are connected to one of thecommon leads or lines designated +A, +B, +C, -A, -B, -C indicating thephase of the incoming voltage and printed on the rear side of plate 29.Finally, each of the reading electrodes 14 printed on the face of theplate 29 are connected to one of the leads 1, 2, 3, 4, 5 on the rearside, each of which can be a switching device be sequentially connectedto the phase-comparison circuit 13 through a wire 15. In FIG. 3, a solidline represents a conducting path on the face of plate 29, while abroken line represents a conducting path on the rear side.

With the above-described arrangement, it will be seen that normally theelectrical field will take a rather wide circuit from one of theelectrodes (say electrode 20) to the diametrically opposed electrode(electrode 23). When the dial hand 12 is positioned adjacent electrode20, for example, the electrical field will pass therethrough, and as aresult of the presence of the material of hand 12, a voltage will beinduced in the reading means 14. This change in voltage can be readilymonitored by known techniques to either indicate the angular position,the speed, or direction of rotation of hand 12. Of particular importanceis the phase difference (time lag between peak voltages) between thevoltage induced in reading means 14 and the voltage applied to any givenone of the electrodes 20-25. This phase difference, measured by theconventional phase comparator circuit 13, will be indicative of theangular orientation of the hand 12 with respect to any convenient fixedreference direction (e.g. with respect to the radial line joiningreading electrode 14 with electrode 23), and can be placed on the powerline by the conventional interfact unit 19 to be received by billingequipment at the interrogating location.

There is thus provided an improved apparatus for remotely determiningthe angular orientation, speed, and/or direction of rotation of objectsby means of a rotating electrical field. It will, of course, beunderstood that the particular embodiments here presented are by way ofillustration of the rotating electric field type meter readingapparatus, and are meant to be in no way restrictive. For example,backing plate 29 could be provided with only one electrode and thebacking plate rotated with a stationary electrode positioned at the 12o'clock position, similar to the embodiment shown in FIG. 5 of my formerU.S. Pat. No. 3,500,365. Numerous other changes and modifications couldbe made, and the full use of equivalents resorted to, without departingfrom the spirit or scope of the invention.

What is claimed is:
 1. An apparatus for remotely monitoring the angularposition, speed, and/or direction of rotation of a member as it rotatesabout an axis of rotation and defines a circumferential pathcomprising:a. means for generating a rotating electric field whichdefines a path parallel to said circumferential path of the rotatingmember and includes said circumferential path therein; b. a readingelectrode means fixedly positioned within said electric field andsymmetrically placed with respect to said axis of rotation for sensing avoltage change responsive to the crossing of said rotating member bysaid rotating electric field and emitting an output signal responsive tosaid voltage change; and c. said means for generating the rotatingelectric field and said reading electrode both being positioned inconfronting, spaced relation to, but in no way mechanically orelectrically connected to said rotating member other than that a portionof said rotating member is within the path of said rotating electricfield.
 2. The apparatus according to claim 1 wherein said readingelectrode means is positioned at the center of said rotating electricfield.
 3. The apparatus according to claim 1 wherein said means forgenerating a rotating electric field comprises:a. source of polyphasevoltage; b. a plate positioned in spaced, confronting, parallel relationto said circumferential path; c. a plurality of exciting electrodesdefining a circular array around a center point aligned with said axisof rotation of said rotating member, successive electrodes beingconnected to successive phases of said polyphase voltage.
 4. Theapparatus according to claim 3 wherein said reading electrode means ispositioned in substantially the same plane as said plurality ofelectrodes which define said circular array.
 5. The apparatus accordingto claim 1 wherein said means for generating a rotating electric fieldcomprises:a. source of polyphase voltage; b. a plate positioned inspaced, confronting parallel relation to said circumferential path; c. aplurality of exciting electrodes defining a circular array around acenter point aligned with said axis of rotation of said rotating member,successive diametrically opposed pairs of said electrodes beingconnected to successive phases of said polyphase voltage source, oneelectrode of each pair connected to the positive side of thecorresponding voltage phase and the other electrode of said pair beingconnected to the negative side of the corresponding voltage phase. 6.The apparatus according to claim 5 wherein said reading electrode meansis positioned in substantially the same plane as said plurality ofelectrodes which define said circular array.
 7. System for determiningthe angular position, speed, and/or direction of rotation of the memberas it rotates about an axis of rotation and defines a circumferentialpath comprising:a. source of polyphase voltage; b. transducer means forreceiving said polyphase voltage and generating a rotating electricfield which defines a path parallel to said circumferential path, saidtransducer means further including a reading electrode means fixedlypositioned within said rotating electric field and symmetrically placedwith respect to said axis of rotation for sensing a voltage changeresponsive to the crossing of said rotating member by said rotatingelectric field and emitting an output signal responsive to said voltagechange; c. said transducer means being positioned in confronting, spacedrelation to, but in no way mechanically or electrically connectedthereto other than that a portion of said rotating member is within thepath of said rotating electric field; d. comparator means receiving asample of the applied voltage from said source of polyphase voltage andsaid signal emitted from said reading electrode means, and translatingthe phase difference of said two signals into an electrical signalindicative of the position of said rotating member.
 8. The apparatusaccording to claim 7 wherein said transducer means comprises:a. a platepositioned in spaced, confronting, parallel relation to saidcircumferential path; b. a plurality of exciting electrodes arranged ina circular array symmetrically positioned with respect to said axis ofrotation, successive ones of said electrodes being connected tosuccessive phases of said polyphase voltage.
 9. The apparatus accordingto claim 8 wherein said reading electrode means is positioned insubstantially the same plane as defined by said circular array ofexciting electrodes.
 10. The apparatus according to claim 7 wherein saidtransducer means comprises:a. a plate positioned in spaced, confronting,parallel relation to said circumferential path; b. a plurality ofexciting electrodes arranged in a circular array symmetricallypositioned with respect to said axis of rotation, successivediametrically opposed pairs of said exciting electrodes being connectedto successive phases of said polyphase voltage source, one electrode ofeach pair connected to the positive side of the corresponding voltagephase and the other electrode of said pair being connected to thenegative side of the corresponding voltage phase.
 11. The apparatusaccording to claim 10 wherein said reading electrode means is positionedin substantially the same plane as defined by said circular array ofexciting electrodes.
 12. System for reading utility meters of the typehaving a plurality of dials encased in a glass front housing, each ofsaid dials having a hand which rotates about an axis of rotationdefining a circumferential path and visually indicating one digit of thenumber signifying the amount of consumption of the utility, said systemcomprising:a. a source of polyphase voltage; b. transducer meansattached to said housing adjacent said glass front in confronting,spaced relationship to said plurality of dials, but mechanically andelectrically unconnected thereto; c. said transducer means receivingsaid polyphase voltage and generating a plurality of rotating electricfields, each of which defines a path parallel to and including thereinsaid circumferential path of the corresponding rotating hand, saidtransducer means further including a reading electrode means fixedlypositioned within each of said rotating electric fields andsymmetrically placed with respect to the axis of rotation of thecorresponding meter hand for sensing a voltage change responsive to thecrossing of said rotating hand by said rotating electric field andemitting an output signal responsive to said voltage change; d.comparator means successively receiving samples of the applied voltagefrom said source of polyphase voltage and said signal emitted from eachof said reading electrode means, and translating the phase difference ofsaid two signals into an electrical signal indicative of the position ofeach of said meter hands.
 13. The system for reading utility metersaccording to claim 12 wherein said transducer means comprises a plateextending parallel to said circumferential path and including thereon aplurality of circular arrays of exciting electrodes, each of saidcircular arrays being arranged around a center point aligned with theaxis of rotation of one of said meter hands, successive electrodes beingconnected to successive phases of said polyphase voltage.
 14. The systemfor reading utility meters according to claim 13 wherein said readingelectrode means comprises a sensing electrode corresponding to each ofsaid circular arrays and positioned in substantially the same planedefined by its corresponding circular arrays of electrodes.
 15. Thesystem for reading utility meters according to claim 11 wherein saidtransducer means comprises a plate extending parallel to saidcircumferential path and a plurality of circular arrays of excitingelectrodes attached to said plate, each of said circular electrodearrays extending around a center point aligned with the axis of rotationof one of the electric meter hands, successive diametrically opposedpairs of said electrodes connected to successive phases of saidpolyphase voltage source, one electrode of each pair connected to thepositive side of the corresponding voltage phase and the other electrodeof said pair being connected to the negative side of the correspondingvoltage phase.
 16. The system for reading utility meters according toclaim 15 wherein said reading electrode means comprises a sensingelectrode corresponding to each of said circular arrays and positionedin substantially the same plane defined by its corresponding circulararrays of electrodes.